Transmitters or transformers, and particularly intrinsically safe transmitters or transformers are used for galvanic separation of circuits according to different standards, where the transmitters can transmit not only energy but also signals and/or data.
In different regulations and standards, for example DIN EN 60079-11, minimum distances for safe separation of circuits and therefore also for the coils or windings of transformers are indicated for different safety classes of operational means. These minimum distances are dependent on the insulation medium, so that the minimum distances are divided into solid insulation, clearance distances, and creepage distances. In a typical insulation class, for example protection level 375 V, the minimal separation distance for solid insulation is 1 mm, for example, the creepage distance in air is 10 mm, and the creepage distance under a protective layer is about 3.3 mm.
Intrinsically safe transmitters are designed and optimized, with regard to their geometry, in such a manner that the required separation distances for a specific protection level are ensured. This can be guaranteed not only by means of wound coils but also by means of printed or etched coils on circuit boards. In this connection, it is advantageous, in the case of printed or etched coils, that no additional winding processes are required, and good reproducibility can be guaranteed. Further advantages can lie in an improved thermal property at the same core volume. Furthermore, the production costs can be lower.
DE 10 2005 041 131 A1 discloses an intrinsically safe transmitter with wound coils, where the windings of the coils are applied to different ring cores on the basis of required insulation distances, which cores are magnetically coupled with one another by way of an additional winding sunk into a circuit board. The transmitter configured in this manner is based on traditional winding technology combined with circuit board technology, where the circuit board is used not only for insulation but also for mechanical fixation.
In US 2011/0140824 A1, a transmitter is proposed, in which the circuits or windings to be insulated are affixed asymmetrically on different circuit boards, which are subsequently connected, one on top of the other, with a magnetic core, to form a transmitter or transformer. In this connection, the core can be formed from two halves, which are glued or stapled together, for example, in order to guarantee mechanical stability.
In US 2011/0095620 A1, a planar transmitter for miniaturized applications is described, having two windings that lie on opposite sides of an insulating substrate. The fundamental physical principle of the transmission of energy or data is based on induction. However, this is not an intrinsically safe transmitter, and no magnetic core is used, either.
In EP 0 715 322 A1, a transmitter or transformer is described, the conductor tracks of which are completely produced using planar technology with a ply structure, in which the conductor tracks are accommodated in a circuit board joined together to form one piece. The conductor track is surrounded by a closed magnetic core.